1. Technical Field
The present invention relates to a card device with an antenna feed terminal for use attached to an electronic device such as a personal computer.
2. Background Art
FIG. 4 shows, in the form of a simplified schematic diagram, an example of the external appearance of a known card device. The card device 41 includes a card case 42, a circuit board 43 disposed inside the card case 42, and an antenna 44 disposed rotatably on the outside of the card case 42 and electrically connected to the circuit board 43.
An antenna rotating shaft 45 is formed of a conductive material on the base end of the antenna 44. In a side wall of the card case 42, there is formed a through-hole for inserting the antenna rotating shaft 45 from the outside into the inside of the card case 42. The antenna rotating shaft 45 inserted via the through-hole from the outside in the inside of the card case 42 is electrically connected to a circuit disposed on the circuit board 43, and thus the antenna 44 is electrically connected to the circuit of the circuit board 43 via the antenna rotating shaft 45.
Because the antenna rotating shaft 45 rotates, it is not desirable to connect the antenna rotating shaft 45 directly to the circuit board 43. If the antenna rotating shaft 45 is directly connected to the circuit board 43, various problems can occur. To avoid these problems, it has been proposed to use a feed terminal 46 such as that shown, in the form of a cross-sectional view, in FIG. 5 to electrically connect the antenna rotating shaft 45 to the circuit of the circuit board 43 (refer to, for example, Japanese Unexamined Patent Application Publication No. 2001-339211). See also Japanese Unexamined Patent Application Publication No. 2002-374111.
In the example shown in FIG. 5, the feed terminal 46 is formed of an electrically conductive material, and includes a connection part 46A for contact connection with the antenna rotating shaft 45, and a circuit connection part 46B for contact connection with a circuit-to-antenna connection land 47 formed on the surface of the circuit board 43. In this structure, the antenna rotating shaft 45 is in contact with connection part 46A of the feed terminal 46, and the circuit connection part 46B of the feed terminal 46 is in contact with the antenna connection land 47 of the circuit board 43, and thus the antenna 44 is electrically connected to the circuit of the circuit board 43 via the antenna rotating shaft 45 and the feed terminal 46. In FIG. 5, reference numeral 48 denotes an interconnection pattern that connects the antenna connection land 47 to a part of the circuit, such as a high frequency circuit part for wireless communication (not shown).
If the antenna rotating shaft 45 is electrically connected to the circuit of the circuit board 43 by using the feed terminal 46 such as that shown in FIG. 5, the following problems can occur. The feed terminal 46 has a structure in which the part 46A in contact with the antenna rotating shaft 45 and the part 46B in contact with the antenna connection land 47 of the circuit board 43 are located side by side when viewed from the upper side of the circuit board 43. This structure of the feed terminal 46, in which the part 46A for connection with the antenna rotating shaft and the part 46B for connection with the circuit are located side by side, makes it difficult to reduce the installation space for the feed terminal 46 on the card device 41. Besides, to ensure high reliability in terms of connection with the antenna rotating shaft 45 or the antenna connection land 47, it is required that the part 46A for connection with the antenna rotating shaft and the part 46B for connection with the circuit should each have a sufficiently large size, and thus it is difficult to reduce the installation space for the feed terminal 46 in the card device 41.
When a signal is transmitted between the antenna 44 and the circuit of the circuit board 43, the signal has to pass through two contacts, that is, the contact between the antenna rotating shaft 45 and the part 46A, for connection with the antenna rotating shaft, of the feed terminal 46, and the contact between the antenna connection land 47 of the circuit board 43 and the circuit connection part 46B of the feed terminal 46. Because the respective two electric conductors are simply placed in contact with each other at each of these two points, a signal transmission loss can occur, and, at worst, even a connection failure can occur. This can result in reduction in reliability of the wireless communication capability provided by the card device 41. Although reliability in terms of connection between the feed terminal 46 and the antenna connection land 47 can be improved by plating the surface of the antenna connection land 47 with gold or the like, the result is an increase in cost.